re PR c/30013 (Multiple flaws in decimal floating-point arithmetic conversions fixed)

gcc/
	PR c/30013
	* config/dfp-bit.c: Don't skip TFmode conversions; move strto*
	declarations to top.
	(DFP_TO_BFP): Use for either XFmode or TFmode.
	(BFP_TO_DFP): Use for either XFmode or TFmode; always use cast
	of BFP_VIA_TYPE.
	* config/dfp-bit.h: Include float.h.
	(LONG_DOUBLE_HAS_XF_MODE, LONG_DOUBLE_HAS_TF_MODE): Define if long
	double is one of these modes, rather than using LIBGCC_HAS_*F_MODE
	which doesn't mean the same thing.
	(BFP_KIND): Use 4 to mean TFmode.
	(BFP_FMT): Specify the number of decimal digits based on the
	number of mantissa digits.
	(BFP_VIA_TYPE): Binary float type to use as cast for sprintf.
	(BFP_TO_DFP, DFP_TO_BFP): Define names for TFmode variants.
	(STR_TO_BFP): Use strtold for XFmode or TFmode.
	(TFtype): Define if TFmode is supported.
	* doc/libgcc.texi (Decimal float library routines): Document
	TF conversion functions.

gcc/testsuite/
	* gcc.dg/dfp/convert-bfp.c: Replace SKIP_LONG_DOUBLE with runtime
	checks for size of long double.
	* gcc.dg/dfp/convert.h: New file.
	* gcc.dg/dfp/convert-bfp-2.c: New test.
	* gcc.dg/dfp/convert-bfp-3.c: Ditto.
	* gcc.dg/dfp/convert-bfp-4.c: Ditto.
	* gcc.dg/dfp/convert-bfp-5.c: Ditto.
	* gcc.dg/dfp/convert-bfp-6.c: Ditto.
	* gcc.dg/dfp/convert-bfp-7.c: Ditto.
	* gcc.dg/dfp/convert-bfp-8.c: Ditto.
	* gcc.dg/dfp/convert-bfp-9.c: Ditto.
	* gcc.dg/dfp/convert-bfp-10.c: Ditto.
	* gcc.dg/dfp/convert-bfp-11.c: Ditto.

From-SVN: r128361

2 files changed, 70 insertions, 36 deletions

diff --git a/gcc/config/dfp-bit.c b/gcc/config/dfp-bit.c
index 6a1bc30..8ee4dec 100644
--- a/gcc/config/dfp-bit.c
+++ b/gcc/config/dfp-bit.c
@@ -34,16 +34,11 @@ Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
 
    Contributed by Ben Elliston  <bje@au.ibm.com>.  */
 
-/* The intended way to use this file is to make two copies, add `#define '
-   to one copy, then compile both copies and add them to libgcc.a.  */
-
-/* FIXME: This implementation doesn't support TFmode conversions.  */
-#if !(defined (L_sd_to_tf) || defined (L_dd_to_tf) \
-      || defined (L_td_to_tf) || defined (L_tf_to_sd) \
-      || defined (L_tf_to_dd) || defined (L_tf_to_td))
-
 #include <stdio.h>
 #include <stdlib.h>
+/* FIXME: compile with -std=gnu99 to get these from stdlib.h */
+extern float strtof (const char *, char **);
+extern long double strtold (const char *, char **);
 #include <string.h>
 #include <limits.h>
 
@@ -471,7 +466,9 @@ INT_TO_DFP (INT_TYPE i)
 #if defined (L_sd_to_sf) || defined (L_dd_to_sf) || defined (L_td_to_sf) \
  || defined (L_sd_to_df) || defined (L_dd_to_df) || defined (L_td_to_df) \
  || ((defined (L_sd_to_xf) || defined (L_dd_to_xf) || defined (L_td_to_xf)) \
-     && LIBGCC2_HAS_XF_MODE)
+     && LONG_DOUBLE_HAS_XF_MODE) \
+ || ((defined (L_sd_to_tf) || defined (L_dd_to_tf) || defined (L_td_to_tf)) \
+     && LONG_DOUBLE_HAS_TF_MODE)
 BFP_TYPE
 DFP_TO_BFP (DFP_C_TYPE f)
 {
@@ -489,7 +486,9 @@ DFP_TO_BFP (DFP_C_TYPE f)
 #if defined (L_sf_to_sd) || defined (L_sf_to_dd) || defined (L_sf_to_td) \
  || defined (L_df_to_sd) || defined (L_df_to_dd) || defined (L_df_to_td) \
  || ((defined (L_xf_to_sd) || defined (L_xf_to_dd) || defined (L_xf_to_td)) \
-     && LIBGCC2_HAS_XF_MODE)
+     && LONG_DOUBLE_HAS_XF_MODE) \
+ || ((defined (L_tf_to_sd) || defined (L_tf_to_dd) || defined (L_tf_to_td)) \
+     && LONG_DOUBLE_HAS_TF_MODE)
 DFP_C_TYPE
 BFP_TO_DFP (BFP_TYPE x)
 {
@@ -502,12 +501,7 @@ BFP_TO_DFP (BFP_TYPE x)
   DFP_INIT_ROUNDMODE (context.round);
 
   /* Use a C library function to write the floating point value to a string.  */
-#ifdef BFP_VIA_TYPE
-  /* FIXME: Is there a better way to output an XFmode variable in C?  */
   sprintf (buf, BFP_FMT, (BFP_VIA_TYPE) x);
-#else
-  sprintf (buf, BFP_FMT, x);
-#endif
 
   /* Convert from the floating point string to a decimal* type.  */
   FROM_STRING (&s, buf, &context);
@@ -543,7 +537,3 @@ DFP_UNORD (DFP_C_TYPE arg_a, DFP_C_TYPE arg_b)
   return (decNumberIsNaN (&arg1) || decNumberIsNaN (&arg2));
 }
 #endif /* L_unord_sd || L_unord_dd || L_unord_td */
-
-/* !(L_sd_to_tf || L_dd_to_tf || L_td_to_tf \
-     || L_tf_to_sd || L_tf_to_dd || L_tf_to_td)  */
-#endif
diff --git a/gcc/config/dfp-bit.h b/gcc/config/dfp-bit.h
index 7c47387..27c6a8a 100644
--- a/gcc/config/dfp-bit.h
+++ b/gcc/config/dfp-bit.h
@@ -30,6 +30,7 @@ Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
 #ifndef _DFPBIT_H
 #define _DFPBIT_H
 
+#include <float.h>
 #include <fenv.h>
 #include <decRound.h>
 #include <decExcept.h>
@@ -49,10 +50,15 @@ Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
 #define LIBGCC2_LONG_DOUBLE_TYPE_SIZE LONG_DOUBLE_TYPE_SIZE
 #endif
 
-#ifndef LIBGCC2_HAS_XF_MODE
-#define LIBGCC2_HAS_XF_MODE \
+/* We need to know the size of long double that the C library supports.
+   Don't use LIBGCC2_HAS_XF_MODE or LIBGCC2_HAS_TF_MODE here because
+   some targets set both of those.  */
+
+#define LONG_DOUBLE_HAS_XF_MODE \
   (BITS_PER_UNIT == 8 && LIBGCC2_LONG_DOUBLE_TYPE_SIZE == 80)
-#endif
+
+#define LONG_DOUBLE_HAS_TF_MODE \
+  (BITS_PER_UNIT == 8 && LIBGCC2_LONG_DOUBLE_TYPE_SIZE == 128)
 
 /* Depending on WIDTH, define a number of macros:
 
@@ -242,6 +248,9 @@ Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
 #elif defined (L_sd_to_xf) || defined (L_dd_to_xf ) || defined (L_td_to_xf) \
  ||   defined (L_xf_to_sd) || defined (L_xf_to_dd) || defined (L_xf_to_td)
 #define BFP_KIND 3
+#elif defined (L_sd_to_tf) || defined (L_dd_to_tf) || defined (L_td_to_tf) \
+ ||   defined (L_tf_to_sd) || defined (L_tf_to_dd) || defined (L_tf_to_td)
+#define BFP_KIND 4
 #endif
 
 /*  If BFP_KIND is defined, define additional macros:
@@ -249,29 +258,48 @@ Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
     BFP_TYPE: The binary floating point data type.
 
     BFP_FMT: The format string for writing the value to a string.
+    The number of decimal digits printed is
+       ceil (nbits / log2 (10.) + 1)
+    as described in David Matula's CACM 19(3) 716-723 June 1968 paper.
 
+    BFP_VIA_TYPE: Type to which to cast a variable of BPF_TYPE for a
+    call to sprintf.
+    
     STR_TO_BFP: The function to read the value from a string.  */
 
 #if BFP_KIND == 1
-/* strtof is declared in <stdlib.h> only for C99.  */
-extern float strtof (const char *, char **);
 #define BFP_TYPE SFtype
-#define BFP_FMT "%e"
+#define BFP_FMT "%.9e"
+#define BFP_VIA_TYPE double
 #define STR_TO_BFP strtof
 
 #elif BFP_KIND == 2
 #define BFP_TYPE DFtype
-#define BFP_FMT "%e"
+#define BFP_FMT "%.17e"
+#define BFP_VIA_TYPE double
 #define STR_TO_BFP strtod
 
 #elif BFP_KIND == 3
-#if LIBGCC2_HAS_XF_MODE
-/* These aren't used if XF mode is not supported.  */
+#if LONG_DOUBLE_HAS_XF_MODE
 #define BFP_TYPE XFtype
-#define BFP_FMT "%e"
-#define BFP_VIA_TYPE double
-#define STR_TO_BFP strtod
-#endif
+#define BFP_FMT "%.21Le"
+#define BFP_VIA_TYPE long double
+#define STR_TO_BFP strtold
+#endif /* LONG_DOUBLE_HAS_XF_MODE */
+
+#elif BFP_KIND == 4
+#if LONG_DOUBLE_HAS_TF_MODE
+#define BFP_TYPE TFtype
+#if LDBL_MANT_DIG == 106
+#define BFP_FMT "%.33Le"
+#elif LDBL_MANT_DIG == 113
+#define BFP_FMT "%.36Le"
+#else
+#error "unknown long double size, cannot define BFP_FMT"
+#endif /* LDBL_MANT_DIG */
+#define STR_TO_BFP strtold
+#define BFP_VIA_TYPE long double
+#endif /* LONG_DOUBLE_HAS_TF_MODE */
 
 #endif /* BFP_KIND */
 
@@ -455,6 +483,9 @@ extern float strtof (const char *, char **);
 #elif BFP_KIND == 3
 #define BFP_TO_DFP	DPD_BID_NAME(__dpd_truncxfsd,__bid_truncxfsd)
 #define DFP_TO_BFP	DPD_BID_NAME(__dpd_extendsdxf,__bid_extendsdxf)
+#elif BFP_KIND == 4
+#define BFP_TO_DFP	DPD_BID_NAME(__dpd_trunctfsd,__bid_trunctfsd)
+#define DFP_TO_BFP	DPD_BID_NAME(__dpd_extendsdtf,__bid_extendsdtf)
 #endif /* BFP_KIND */
 
 #elif WIDTH == 64
@@ -467,6 +498,9 @@ extern float strtof (const char *, char **);
 #elif BFP_KIND == 3
 #define BFP_TO_DFP	DPD_BID_NAME(__dpd_truncxfdd,__bid_truncxfdd)
 #define DFP_TO_BFP	DPD_BID_NAME(__dpd_extendddxf,__bid_extendddxf)
+#elif BFP_KIND == 4
+#define BFP_TO_DFP	DPD_BID_NAME(__dpd_trunctfdd,__bid_trunctfdd)
+#define DFP_TO_BFP	DPD_BID_NAME(__dpd_extendddtf,__bid_extendddtf)
 #endif /* BFP_KIND */
 
 #elif WIDTH == 128
@@ -479,6 +513,9 @@ extern float strtof (const char *, char **);
 #elif BFP_KIND == 3
 #define BFP_TO_DFP	DPD_BID_NAME(__dpd_extendxftd,__bid_extendxftd)
 #define DFP_TO_BFP	DPD_BID_NAME(__dpd_trunctdxf,__bid_trunctdxf)
+#elif BFP_KIND == 4
+#define BFP_TO_DFP	DPD_BID_NAME(__dpd_extendtftd,__bid_extendtftd)
+#define DFP_TO_BFP	DPD_BID_NAME(__dpd_trunctdtf,__bid_trunctdtf)
 #endif /* BFP_KIND */
 
 #endif /* WIDTH */
@@ -487,9 +524,12 @@ extern float strtof (const char *, char **);
 
 typedef float SFtype __attribute__ ((mode (SF)));
 typedef float DFtype __attribute__ ((mode (DF)));
-#if LIBGCC2_HAS_XF_MODE
+#if LONG_DOUBLE_HAS_XF_MODE
 typedef float XFtype __attribute__ ((mode (XF)));
-#endif /* LIBGCC2_HAS_XF_MODE */
+#endif /* LONG_DOUBLE_HAS_XF_MODE */
+#if LONG_DOUBLE_HAS_TF_MODE
+typedef float TFtype __attribute__ ((mode (TF)));
+#endif /* LONG_DOUBLE_HAS_TF_MODE */
 
 typedef int SItype __attribute__ ((mode (SI)));
 typedef int DItype __attribute__ ((mode (DI)));
@@ -566,14 +606,18 @@ extern DFP_C_TYPE INT_TO_DFP (INT_TYPE);
 #if defined (L_sd_to_sf) || defined (L_dd_to_sf) || defined (L_td_to_sf) \
  || defined (L_sd_to_df) || defined (L_dd_to_df) || defined (L_td_to_df) \
  || ((defined (L_sd_to_xf) || defined (L_dd_to_xf) || defined (L_td_to_xf)) \
-     && LIBGCC2_HAS_XF_MODE)
+     && LONG_DOUBLE_HAS_XF_MODE) \
+ || ((defined (L_sd_to_tf) || defined (L_dd_to_tf) || defined (L_td_to_tf)) \
+     && LONG_DOUBLE_HAS_TF_MODE)
 extern BFP_TYPE DFP_TO_BFP (DFP_C_TYPE);
 #endif
 
 #if defined (L_sf_to_sd) || defined (L_sf_to_dd) || defined (L_sf_to_td) \
  || defined (L_df_to_sd) || defined (L_df_to_dd) || defined (L_df_to_td) \
  || ((defined (L_xf_to_sd) || defined (L_xf_to_dd) || defined (L_xf_to_td)) \
-     && LIBGCC2_HAS_XF_MODE)
+     && LONG_DOUBLE_HAS_XF_MODE) \
+ || ((defined (L_tf_to_sd) || defined (L_tf_to_dd) || defined (L_tf_to_td)) \
+     && LONG_DOUBLE_HAS_TF_MODE)
 extern DFP_C_TYPE BFP_TO_DFP (BFP_TYPE);
 #endif